Non slip system for a deformable driving band

ABSTRACT

The deformable driving band (3) or similar comprises passage means (2) passing through the band and opening out, towards the inside, at right angles to pockets (5) or similar provided in a compressible strip (6) extending over the whole driving band, the assembly being such that a suction phenomenon increasing grip is created by the compressible strip (6) and the packets (5) in deformation zone of the driving band (3) corresponding to an expansion phase of said pockets (5).

The invention relates to a non slip system for a deformable driving bandor similar.

Such a driving band may be formed by the running strip of a pneumatictire for a vehicle of any type, more especially a light, utility orheavy vehicle. In another application, such a driving band may be formedby an endless transporter belt.

The aim of the invention is especially to improve the grip of thedeformable driving band at the surface of the objects with which itcomes into contact. Thus, in the case of vehicle tires, the air of theinvention is to improve the grip of the tires on the ground, moreespecially in the case of rain, snow or ice; in the case of atransporter belt, the air of the invenion is to improve the grip of saidtransporter belt with the material or with the objects to betransported.

According to the invention, a non slip system for a deformable drivingband or similar is characterized by the fact that it comprises passagemeans for passing through the driving band and emerging inwardly atright angles to pockets or similar provided in a compressible stripextending along the whole of the driving band, the assembly being suchthat a suction phenomenon increasing the grip is created by thecompressible strip and the pockets in a deformation zone of the drivingband corresponding to an expansion phase of said pockets.

The strip of compressible material may be formed by a part of thedriving band itself; each passage means and the pocket (or similar whichis associated therewith then form a blind channel slanting with respectto the direction perpendicular to the bearing surface, more especiallyso that there is progressive ejection of the air from the channel,before the outer end of the channel comes into contact with the bearingsurface, this ejection phase being followed by a suction phase.

The slant of each channel may be provided so that, for the normaldirection of travel of the driving band with respect to the bearingsurface, the outer end of the channel only comes into contact with thebearing surface after the channel has cleared the beginning of thecontact zone with this bearing surface.

Each blind channel is entirely located in the driving band which in away plays also the role of the compressible strip, as pointed out above,this driving band undergoing first of all crushing in the deformationzone, which causes air to be ejected from the channel.

In the case of a pneumatic tire, each blind channel is located entirelyin the running strip which is situated radially on the outside of thecasing.

In a variant, each passage means and the pocket (or similar) which isassociated therewith are formed by the combination of a blind channelslanting with respect to the direction perpendicular to the bearingsurface and means for facilitating detachment of the channel.

These means for facilitating detachment of the channel may be formed byan auxiliary channel, with reduced cross section, situated in front ofthe main channel in the travel direction of the driving band withrespect to the bearing surface, this auxiliary channel communicating atleast with a zone of the main channel situated towards the blind end ofthis main channel. This auxiliary channel may be formed by a grooveextending over the whole length of the main channel.

According to another possibility, the means for facilitating detachmentof the blind channel may be formed by providing the channel in twoparts, in particular two half channels with their concave sides turnedtowards each other provide in two blocks of material separated by a slitof zero width, these blocks being jointing during crushing of thedriving belt and moving slightly away from each other during thedecompression phase of the band, which causes detachment of the channel.

According to another aspect of the invention, the blind channels may beorientated in the left and/or right transverse direction so as toprovide better grip laterally in bends in the road. The channels may beorientated in a direction having a component in the transverse directionand in the longitudinal direction.

The lateral as also the longitudinal tread of the running strip may beslanting through the same angle as that of the blind channels,particularly so as to facilitate removal from the mold.

The invention also relates to pneumatic tyres for vehicles, transporterbelts and, more generally, deformable driving band or similar equippedwith the non slip system in accordance with the invention.

The invention will be better understood from the detailed description ofparticular embodiments described with reference to the accompanyingdrawings but which are in no wise limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 of these drawings is a schematical cross section of a pneumatictire equipped with a system in accordance with the invention;

FIG. 2 is a partial section through II--II of FIG. 1;

FIG. 3 is a schematical elevational view of the pneumatic tire;

FIG. 4 illustrates, in a schematical partial cross section anotherembodiment;

FIG. 4a is a partial section through IV--IV of FIG. 4;

FIG. 5 is an elevational view of the running strip of a pneumatic tirehaving the non slip system according to the invention;

FIG. 6 is a partial developed section through VI--VI of FIG. 5;

FIG. 7 is a cross section of the running strip;

FIG. 8 is a schematical representation of the pneumatic tire and of itsrotational direction;

FIG. 9 is a partial section, through the mean longitudinal plane of thepneumatic tire, of the running strip;

FIG. 10 is a partial longitudinal section of a driving band formed bythe running strip of the pneumatic tire provided with the non slipsystem according to the invention;

FIG. 11 is a bottom view with respect to FIG. 10;

FIG. 12 shows, similarly to FIG. 10, another embodiment;

FIG. 13 is a bottom view with respect to FIG. 12;

FIG. 14 shows, similarly to FIG. 10, another embodiment;

FIG. 15 is a bottom view with respect to FIG 14;

FIG. 16 is a schematical partial cross section of the running strip;

FIG. 17 finally is a partial elevational view of the running strip.

Referring to FIG. 1, there is shown a pneumatic tire 1 equipped with thesystem for improving the grip thereof. This system comprises passingmeans formed by radially orientated holes 2 passing through the runningstrip 3 as well as the casing 4 and opening inwardly of the casing ofthe tire, at right angles to pockets 5 or similar provided in a strip 6formed from a compressible material.

This strip 6, as shown in FIG. 3, extends along the whole innerperiphery of the casing 4 and forms a closed ring.

Pockets 5, as shown in FIG. 2, may have any shape, for example an oblongelongate shape. Several rings of pockets 5 are provided cross the widthof the cross section; as shown in FIG. 2, the pockets 5 of a ring arestaggered in quincunx arrangement with respect to the pockets 5 of thedirectly adjacent rings so as to allow permanent contact with the road,one row of pockets taking over from another row in the rotationalmovement. Holes 2 open out advantageously at longitudinal ends ofpockets 5. Holes 2, as shown in FIG. 2, are preferably disposed so thattheir centers are aligned along straight lines D situated in planespassing through the axis of rotation of the tire. Holes 2 may be in astraight line, a broken line, a conical line or follow another curve.

Flexible wall 7 is sealingly fixed more especially by bonding, to theinside of casing 4 so that strip 6 is imprisoned between this flexiblewall 7 and the casing. The pneumatic tire may be of the inner tube type,in which case the inner tube is applied against wall 7 or of thetubeless type or of the solid type.

Strip 6 may be in the form of a solid strip made from an elastomermaterial or any appropriate material.

In a variant, this strip 6 may be in the form of a sealed annularchamber, with valve, containing a gas, more especially air, under anadjustable pressure counterbalancing that of the tire, or even varyingas a function of the load of the vehicle.

The whole is such that in zone E (FIG. 3) of the tire which comes intocontact with the ground and which is crushed under the effect of theload supported by the tire, the compression of strip 6 and of thepockets causes the air contained in these pockets to be expelled throughholes 2. In zone S (FIG. 3) of the tire which leaves the ground, thestrip is progressively relieved of the load and pockets 5 resume theirvolume by sucking in air through holes 2.

A suction cup phenomenon is thus created by aspiration which increasesthe grip of the tire on the ground.

In the variant shown in FIG. 4, the compressible strip system 6 withpockets 5 may be placed radially outside the casing 4. This casing doesnot then have holes 2 passing therethrough. This latter variant may bemore particularly suitable for worn tires which are intended to beretreaded; strip 6 with pockets 5 may be inserted during retreadingbetween the casing and the added running strip provided with holes 2.

If need be, strip 6 and strip 3 may form one and the same strip, pockets5 being provided in a region of strip 3 serving as strip 6.

As shown in FIG. 4a, pockets 5 extend in the peripheral direction,substantially at right angles with respect to the radial direction. Inthe embodiments shown in FIGS. 4 and 4a, a single radial hole 2 isprovided at a longitudinal end of a pocket 5. So as to avoid having tofit the tire in a given direction, pockets 5 are divided into twoalternating series R1, R2 orientated in opposite directions. Whateverthe direction of rotation of the tire, for one of the series, pockets 5forming blind channels are situated in front of the associated hole 2.

The crushing phenomenon of the tire against the ground and so thesuction cup phenomenon described above is accentuated during a loadtransfer, for example during braking or in a bend, which contributes toimproving the grip on a wet, icy, or snow bound road; in this case, theperforations form additional gripping means which increase the grip onthe ground particularly during braking.

This system may be used for any vehicle, whether the tire is made froman elastomer material or from a plastic material or from anothermaterial.

The connection between strip 6 and walls 7 (FIG. 1) may be provided byan assembly of circumferential grooves and ribs provided respectively onthe faces of the strip and of the wall which come into contact.

The improvement of the grip is obtained in the case of rain, snow, orice, also on a normal road as well as during braking on all roads.

The number of rows of pockets, the shape of these pockets as well as thearrangement and the shape of holes 2 are chosen depending on the type oftire so as to obtain the most satisfactory results. In this applicationto pneumatic tires, the width 1 of each pocket may be severalmillimeters. The thickness h in the radial direction of strip 6 could beof the order of 10 mm, where as the thickness of wall 7 could be of theorder of 2 to 10 mm.

Edges 6a, 6b of strip 6 are preferably bevelled so as to match thecontour of the cross section of the tire.

This system may be applied to pneumatic tires of all types, includingtires for aircraft under-carriages.

With a pneumatic tire equipped, with this system, a smooth road surfaceis no longer a disadvantage. This system opposes the "aquaplaning"phenomenon. On a snow bound road, the passage means which compriseorifices opening into the running strip play the role of additionalgripping means.

When the compressor strip 6 is in the form of a closed and sealedannular chamber containing a pressurized gas, the vehicle then rests ontwo air cushions, whence improved comfort; the system further offersgreater safety by reducing the risks of the inner tube properly speakingbursting in most cases.

More generally, the invention applies to a deformable driving band orsimilar.

In the case of an endless transporter belt, the transporter belt passesover rollers at both ends and is wound through a half circle. In thewinding zone of the transporter belt, we find again deformations similarto those of zones E and S of the pneumatic tire.

In the region where the transporter belt leaves a roller, the pockets 5of a compressible strip 6 fixed on the inner surface of the transporterbelt will be in an expansion phase with creation of a suction phenomenonthrough the passage mean formed by holes 2 passing through thetransporter belt. By placing the object to be transported in contactwith the transporter belt in this zone where a suction phenomenonoccurs, said objects may be subjected to a suction cup effect apply themagainst the belt; this suction cup effect may be maintained during thewhole time that the object is transported by the belt, if a sufficientseal is provided between the surface of the object and orifices 2.

The dimensions, the shape and the number of pockets 6 and of orifices 2are determined as a function of the transporter belt to be equipped withthe system of the invention.

The transporter belt, which then forms the deformable driving belt 3, isgenerally made from an elastomer material and a compressible strip 6 isfixed against this strip, in a way similar to that shown in FIG. 4.

FIGS. 5 to 9 relate to another embodiment.

As shown in FIG. 5, the running strip B of the pneumatic tire, whichforms the deformable driving belt, comprises passage means 2 passingthrough this belt and opening, on the inside, at right angles to pockets5 or similar. The assembly is such that a suction phenomenon increasingthe grip is created in a deformation zone S (FIG. 8) of the runningstrip in contact with the bearing surface formed by the ground 10. Thiszone S corresponds to the part of the pneumatic tire which leaves theground, strip B being relieved progressively of the load and pockets 5resuming their volume and sucking in the air through the passage means 2formed by the holes.

Each passage means 2 and pocket 5 which is associated therewith form ablind channel 11 slanting by an angle α with respect to the direction Δperpendicular to the bearing surface 10, so that there is progressiveejection of air from the channel before the outer end 12 of the channelcomes into contact with the bearing surface 10 (see particularly FIG.9).

When the running strip is not deformed, channel 11 is rectilinear; thepart of this channel situated towards the blind end plays the role ofpocket 5, whereas the part of channel 11 situated towards end 12 playsthe role of passage means 2.

The slant of each channel 11, with respect to direction Δ, is providedso that for the normal direction of movement of the driving band (i.e.in the case of a pneumatic tire for the forward travel directionillustrated by arrow F, with respect to ground 10), the outer end 12 ofthe channel only comes into contact with the ground 10 after the channel11 has cleared (see FIG. 9) the beginning 13 of the zone 14 of the tirein contact with the ground 10.

As shown in the drawings, channels 11 are independent from each otherand are formed in blocks 15 of the running strip separated by a systemof longitudinal and transverse grooves 16.

Advantageously, the slant of channel 11 is such that, when the outer end12 of the channel comes into contact with the ground 10 (see FIG. 9),the other blind end of channel 11 is situated beyond and outside thelimit 17 of contact zone 14. Angle α is preferably equal to or greaterthan 60°.

The cross section of each blind channel 11 may have a greater dimensionL in a direction parallel to the bearing surface 10. It should howeverbe noted that the cross section of channel 11 may have shapes verydifferent from those shown in the drawings and which are substantiallyrectangular.

The operation of the non slip system follows from the precedingexplanations.

The progressive crushing of the running strip B, in zone E (FIG. 8 and9) of the pneumatic tire which advances in contact with the ground,drives out the air contained in channels 11.

When the outer end 12 of a channel 11 is closed by coming into contactwith ground 10, a suction phenomenon is produced by expansion of thepart 11a (FIG. 9) of the channel situated outside the bearing surface 14of the tire.

More precisely, part 11a is situated outwardly of a cylindrical surfacewith vertical generatrices having the contact surface 14 as basis.

The outer end 12 or orifice of each channel 11 will not tend to choke upbecause of the ejection of air at the time of crushing.

In the case of high speed, or even when the vehicle is loaded, theefficiency of the system is accentuated during braking by the loadtransfer which causes a greater crushing effect and so a strongersuction.

FIGS. 10 to 17 show other embodiments.

As shown in FIG. 10, the running strip B of the pneumatic tire, whichforms the deformable driving belt, comprises passage means 2 passingthrough this strip and opening, on the inside, at right angles topockets 5 or similar. The assembly is such that a suction phenomenon iscreated by aspiration, increasing the grip, in a deformation zone S ofthe strip in contact with the bearing surface formed by ground 10.

Each passage means 2 and the pocket 5 are formed by the combination of ablind channel 21 slanting through an angle α with respect to thedirection Δ perpendicular to the bearing surface 10 and means 22 forfacilitating detachment of channel 11.

In the embodiment shown in FIGS. 10 and 11, means 22 comprise anauxiliary channel 23, with reduced cross section, with respect to thatof channel 21. This channel 23 is situated, with respect to channel 21,forwardly in the direction of movement or of rotation R of strip B withrespect to ground 10. If we take as reference direction the forwardtravel direction F of the vehicle, channel 23 is situated behind channel21. In the embodiment shown in FIGS. 10 and 11, a slanting dividing wall24 separates channel 21 from channel 23, this driving wall 24 beingstopped at 25 at a certain distance from the bottom of blind channel 21.Space 26 provides communication between the auxiliary channel 23 and azone of channel 21 situated towards the blind end of this channel. Thedividing wall 24 will then remain until maximum wear of the runningstrip B.

The operation of means 22 is the following.

At the moment when strip B, in the region of the outer end of channels21, 22 begins to leave the ground, channel 23 which has a reducedsurface leaves the ground first. The force required for detaching theend of channel 23 with reduced section from the ground will be smallerthan for a larger section channel. Detachment of channel 23 allows airto enter channel 21 through the communication 26 and so facilitatesdetachment of this channel 21 with respect to the bearing surface 10.Resistance to travelling will then be reduced.

FIGS. 12 and 13 show a variant in which the auxiliary channel is formedby a groove 23a, having a reduced section with respect to channel 21 andextending over the whole length of this channel. This groove 23a is alsosituated behind channel 21 in the travel direction F of the vehicle, orin front of this channel if we consider the rotational direction R ofthe strip at the point of contact thereof with the ground.

In the variant shown in FIGS. 14 and 15, means 22 are formed byproviding channel 21 in two parts 21a, 21b, for example two halfchannels 21a, 21b with a semi circular section, with their concave sidesturned towards each other. These two half channels are provided in twoblocks 27, 28 of strip B separated by a slit 29 of zero width. Blocks27, 28 may be formed by transverse strips. Blocks 27, 28 are jointingduring crushing of strip B, i.e. hermetically sealed.

The two half channels 21a, 21b disposed one against the other form againthe blind channel 21.

When the region of strip B containing channels 21a, 21b begins to berelieved of the weight of the vehicle, blocks 27, 28 move slightly awayfrom each other while causing slit 29 to reappear which allows air toenter into the channel formed by the assembly 21a, 21b. Detachment ofthis channel is thus facilitated.

As shown in FIG. 16, channels 21 may be slanted in the left or righttransverse direction or in both directions so as to provide betterlateral grip in left hand and right hand bends.

As shown in FIG. 17, channels 21 may be orientated in a direction Dhaving a component t in the transverse direction and 1 in thelongitudinal direction.

As can be seen in FIGS. 10 and 12, the transverse tread 30 of therunning strip, which allows the removal of water, may be slanted throughthe same angle as that of channels 21. Removal from the mold is thusfacilitated and the grip is more efficient on roads, particularly in thecase of snow.

As shown also in FIG. 16, the longitudinal tread 31 of the running stripmay be slanted through the same angle as channels 21 orientated in thetransverse direction.

This parallelism between the tread and the channels allows the angle oforientation of the channels to be reduced without reducing the depth ofthe tread. It is also possible to reduce the thickness of the runningstrip.

It should be noted that the blind end of the channels forms, in a mannerof speaking, the pocket 5 which is situated in the running strip Bformed from an elastomer material, compressible in the deformabledirection or which is crushed under the effect of a load.

The slant angle α of the channels is less than or equal to 90°, on oneside or other of direction Δ.

The non slip system of the invention improves the grip as well as roadholding. Driving is then safer; the driver has greater steering controlmore especially in bends. Comfort is improved by a flexibility andsuppleness of the pocket structure.

The braking distances are reduced.

I claim:
 1. A non slip system for a deformable driving band having abearing surface comprising passage means passing through the drivingband, said passage means comrising channels having an outer open end atsaid bearing surface, said channels being slanted with respect to adirection perpendicular to said bearing surface, each channel comprisingtwo channel parts having concave sides turned towards each other, saidtwo channel parts being provided in two transverse blocks of materialseparated by a slit, said slit providing sealing of the blocks duringcrushing of the driving band, and moving slightly away from each otherduring decompression of the band.
 2. A non slip system according toclaim 1 in which the slit has a zero width.
 3. A non slip systemaccording to claim 1 in which said channels open, towards the inside,into pockets provided in a compressible strip extending along the wholedriving band.
 4. A non slip system according to claim 3 in which eachchannel and the pocket which is associated therewith form a blindchannel slanting with respect to a direction perpendicular to thebearing of said surface of said band so that there is progressiveejection of the air from the channel, before the outer end of a channelenters into contact with a surface, this ejection phase being followedby a suction phase.
 5. A non slip system according to claim 4 whereinthe slant of each channel is provided so that for the normal directionof movement of the driving band with respect to a surface with which thedriving band comes in contact, the outer open end of the channel onlycomes into contact with said surface after the channel has cleared thebeginning of the contact zone with said surface.
 6. A non slip systemaccording to claim 5 wherein the slant of the channel is such that whenthe outer open end of the channel comes into contact with said surface,the inner end of the channel is situated beyond and outside the limit ofthe contact zone with said surface.
 7. A non slip system according toclaim 1 wherein the cross section of each of the said channels has itslarger dimension in a direction parallel to said bearing surface.
 8. Anon slip system according to claim 1 wherein said channels compriseblind channels from which air is ejected during crushing of the band andinto which air is sucked during decompression of the band.
 9. A non slipsystem according to claim 1, in which the channels are slanted intransverse direction.
 10. A non slip system according to claim 1 inwhich the channels are oriented in a direction having a component in thetransverse direction and a component in the longitudinal direction. 11.A non slip system according to claim 9 in which the drive band has atread, said tread of the drive band having grooves slanted in transversedirection through the same angle as the channels.
 12. A non slip systemaccording to claim 1 wherein said deformable driving band comprises apneumatic tire for vehicles, said tire including a casing and a runningstrip wherein each channel is situated entirely in the running stripwhich is situated radially on the outside of the casing.
 13. A non slipsystem according to claim 1 in which the channel is provided in two halfchannels with a semi-circular section.